People who have been dually diagnosed with a severe mental illness and a substance abuse disorder are at an elevated risk for contracting blood-borne infections, such as HIV, hepatitis B, and hepatitis C virus (HCV). Prevention, early detection, and treatment for these diseases are essential for this particular population. Research has shown that rates of HCV infection are 11 times higher in people with mental illnesses than in the general population. People with mental health illnesses and those with dual diagnoses should receive basic CDC-recommended services for risk screening and testing of HIV infection, AIDS, and hepatitis. They should also receive hepatitis A and B immunizations, risk reduction counseling, and referrals for medical care. However, most people with severe mental illnesses and substance abuse disorders do not receive the care they need. The STIRR (screen, test, immunize, reduce risk, and refer) intervention will provide necessary prevention and treatment services to an at-risk, under-treated population. This study will determine the effectiveness of the STIRR intervention in increasing rates of testing, immunization, referral, and treatment for blood-borne diseases, such as hepatitis and HIV, in people with both a mental disorder and a substance abuse disorder.